Mean and Turbulence Properties of a Neutrally Buoyant Round Jet in a Wave Environment

Abstract

An experimental study of a turbulent round jet discharged into a regular wave field is presented. The particle image velocimetry (PIV) technique was employed to measure instantaneous velocity fields of the flow. Quantitative mean and turbulence properties were obtained using ensemble- and phase-averaged methods. Both the jet potential core region and self-similar region were measured. Three different wave heights were used to examine the effect of wave steepness on the jet properties. Measurements were also taken at three different phases to examine the wave phase effect. Experimental results demonstrate that the mean jet width, turbulence intensity, and Reynolds stress increased significantly when the jet was acted on by the waves. In addition, the jet mean kinetic energy decreased whereas the turbulent kinetic energy increased when the jet was under the waves, indicating an increase in turbulence. The wave phase has an insignificant effect on the both the mean and turbulence properties. The turbulent kinetic energy budget in the self-similar region at different wave conditions was also examined. It was found that the turbulent production, advection, and dissipation terms all increase with the increase of the wave height.